Distribution of polymorphic forms of troponin components and tropomyosin in skeletal muscle.

Specific antibodies have been used to show that in adult skeletal muscle the slow and fast forms of the components of the troponin complex are located in type I and type II fibres respectively. alpha-Tropomyosin is restricted to type II cells. During development, as a result of changes in innervation and in certain diseased stages, both the slow and fast polymorphic forms of the troponin components are present in the same cell.